Collet Insert Downwardly Deployable in Receiver

This application is a continuation of U.S. patent application Ser. No. 19/377,634, filed Nov. 3, 2025, which is a continuation of U.S. patent application Ser. No. 18/933,954, filed Oct. 31, 2024, now U.S. Pat. No. 12,458,410, which is a continuation of U.S. patent application Ser. No. 18/055,399, filed Nov. 14, 2022, now U.S. Pat. No. 12,137,944, which is a continuation of U.S. patent application Ser. No. 17/564,784, filed Dec. 29, 2021, now U.S. Pat. No. 11,497,533, which is a continuation of U.S. patent application Ser. No. 16/686,122, filed Nov. 16, 2019, now U.S. Pat. No. 11,234,738 which claims the benefit of U.S. Provisional Application No. 62/811,250, filed Feb. 27, 2019, and U.S. Provisional Application No. 62/768,732, filed Nov. 16, 2018, each of which is incorporated by reference in its entirety herein, and for all purposes.

The present invention generally relates to pivotal bone anchor assemblies for use in bone surgery, particularly spinal surgery.

Bone screws are utilized in many types of spinal surgery in order to secure various implants to vertebrae along the spinal column for the purpose of stabilizing and/or adjusting spinal alignment. Although both closed-ended and open-ended bone screws are known, open-ended screws are particularly well suited for connections to rods and connector arms, because such rods or arms do not need to be passed through a closed bore, but rather can be laid or urged into an open channel within a receiver or head of such a screw.

Typical open-ended bone screws include a threaded shank with a pair of parallel projecting branches or arms which form a yoke defining slot or channel having different shapes, such as U-shaped and square shaped, for example, to receive a rod. Hooks and other types of connectors, as are used in spinal fixation techniques, may also include open ends for receiving rods or portions of other structure.

A common mechanism for providing vertebral support is to implant bone screws into certain bones which then in turn support a longitudinal structure such as an elongate rod, or are supported by such a rod. Bone screws of this type may have a fixed head or receiver relative to a shank thereof. In the fixed bone screws, the rod receiver head cannot be moved relative to the shank and the rod must be favorably positioned in order for it to be placed within the receiver head. This is sometimes very difficult or impossible to do. Therefore, pivotal or polyaxial bone screws are commonly preferred. Open-ended polyaxial bone screws typically allow for pivoting and rotation of the separate receiver about the shank in one or more planes until a desired rotational position of the receiver is achieved by fixing such position relative to the shank during a final stage of a medical procedure when an elongate rod or other longitudinal connecting member is inserted into the receiver, followed by a locking set screw or other closure.

Briefly described, one embodiment of the present disclosure comprises a pivotal bone anchor assembly for securing an elongate rod to patient bone. The pivotal bone anchor system generally includes a shank having a head and an anchor portion, a receiver having an axial bore and an open channel for receiving the elongate rod, and a collet insert that is top loadable into a first upper position within the axial bore of the receiver. The collet insert includes a lower collet-type chamber or pocket for receiving the shank head. The bone anchor assembly also includes a pressure ring that is uploadable into the collet pocket prior to the shank head, and having an upper surface for engaging the elongate rod. After receiving the shank head within the collet pocket below the pressure ring, the collet insert and pressure ring are downwardly deployable together with the shank head into a second position within the axial bore to capture the shank head within the bone anchor assembly. With the collet insert in the second position, the pressure ring is operable to transfer an applied pressure from the elongate rod positioned in the open channel to the shank head to lock an angular position of the shank relative to the receiver.

The invention will be better understood upon review of the detailed description set forth below taken in conjunction with the accompanying drawing figures, which are briefly described as follows.

Those skilled in the art will appreciate and understand that, according to common practice, various features and elements of the drawings described above are not necessarily drawn to scale, and that the dimensions and relative positions between the features or elements may be expanded, reduced or otherwise altered to more clearly illustrate the various embodiments of the present disclosure depicted therein.

The following description, in conjunction with the accompanying drawings described above, is provided as an enabling teaching of exemplary embodiments of a pivotal bone anchor apparatus or assembly, together with methods for assembling and using the pivotal bone anchor apparatus or assembly. As described below, the apparatuses, assemblies, and/or methods of the present disclosure can provide several significant advantages and benefits over other pivotal bone anchors known in the art. However, the recited advantages are not meant to be limiting in any way, as one skilled in the art will appreciate that other advantages may also be realized upon practicing the present disclosure.

Furthermore, those skilled in the relevant art will recognize that changes can be made to the described embodiments while still obtaining the beneficial results. It will also be apparent that some of the advantages and benefits of the described embodiments can be obtained by selecting some of the features of the embodiments without utilizing other features, and that features from one embodiment may be interchanged or combined with features from other embodiments in any appropriate combination. For example, any individual or collective features of method embodiments may be applied to apparatus, product or system embodiments, and vice versa. Accordingly, those who work in the art will recognize that many modifications and adaptations to the embodiments described are possible and may even be desirable in certain circumstances, and are a part of the disclosure. Thus, the present disclosure is provided as an illustration of the principles of the embodiments and not in limitation thereof, since the scope of the invention is to be defined by the claims.

1 FIG. 10 10 10 20 22 23 40 22 100 126 134 104 106 70 100 22 126 106 14 150 190 70 106 50 106 70 190 70 10 22 20 14 20 14 Referring now in more detail to the drawing figures, wherein like parts are identified with like reference numerals throughout the several views,illustrates a representative embodiment of a pivotal bone anchor apparatus or assembly(hereinafter referenced to as “the assembly”) for securing an elongate rod to patient bone in spinal surgery. The assemblygenerally includes a bone anchor, such as shank, having a capture portion, such as shank head, at a proximal end, and an anchor portion or shank bodyextending distally from the shank headfor securement to patient bone. The assembly also generally includes a receiverhaving an internal cavityin a base portionand two upright armsextending upwardly from the base portion to define a rod channelfor receiving an elongate rod. The receivercan be initially pivotably secured to the shank headwith a number of separate internal components that have been pre-assembled into the internal cavityand the rod channelto form a receiver sub-assembly. These components generally include a collet insertand a pressure ring. After an elongate rodhas been positioned within a lower portion of the rod channel, a closurecan be threadably or otherwise secured into an upper portion of the rod channelto apply pressure to an upper surface of the elongate rod, which in turn applies pressure to the upper surface of the pressure ring, thereby locking both the elongate rodand the pivotal bone anchor assemblyinto a final locked position. As discussed in more detail below, the shank headis configured to provide a multi-planar pivotable connection between the shankand the receiver sub-assemblyprior to fixing the shankin a desired position with respect to the receiver sub-assembly.

2 3 FIGS.- 20 22 23 40 22 48 49 20 40 44 42 22 48 40 40 44 48 42 20 20 21 With reference to, the bone anchor or shankgenerally comprises the capture portion or shank headat a proximal end, and an anchor portion or shank bodyextending distally from the shank headtoward a tipat a distal end. The shankis elongate, with the shank bodyhaving a helically wound bone implantable thread(single, dual, or multiple-lead thread form) extending from near a necklocated adjacent to the shank head, to a distal tipof the bodyand extending radially outwardly therefrom. During use, the shank bodyutilizing the threadfor gripping and advancement is implanted into the vertebra (not shown) of a patient leading with the tipand driven down into the vertebra with an installation or driving tool (also not shown), so as to be implanted in the vertebra to near the neckof the shank, as more fully described in the paragraphs below. The shankhas a longitudinal axis, or axis of rotation, that is generally identified by the reference numeral.

42 40 42 40 44 14 44 42 20 The non-threaded neckextends axially upward from the shank body. The neckmay be of the same or is typically of a slightly reduced radius as compared to an adjacent upper end of the shank bodywhere the threadterminates, with the reduced radius providing for increased angulation of the receiver sub-assemblyrelative to the shank. In one aspect the threaded shank bodyand the non-threaded neckcan together define an anchor portion of the shank.

42 22 40 40 22 10 30 32 32 30 24 26 22 30 42 22 Extending further axially upwardly and outwardly from the neckis the shank headthat provides a connective or capture structure disposed at a distance from the shank body, and thus at a distance from the vertebra when the shank bodyis implanted in such vertebra. The shank headof the pivotal bone anchor assemblygenerally has a partial spherical shape defining a hemisphere planeat a maximum width perpendicular to the longitudinal axis, and a partial spherical outer surfaceextending above and below the hemisphere plane. As shown in the drawings, the partial spherical outer surfacemay have a single common radius as it extends above the hemisphere planeto an annular planar top surfaceand an internal driving tool engagement structureformed into the top of the shank head, and as it extends below the hemisphere planeto the neck. It is foreseen, however, that other shapes and/or configurations for the shank headare also possible and considered to fall within the scope of the present disclosure.

28 24 26 26 24 28 40 26 27 26 21 26 21 26 27 28 26 40 20 14 40 100 Located adjacent to the partial spherical outer surfaceis an annular planar top surfacethat surrounds an internal drive featureor drive socket. The illustrated internal drive featureis an aperture formed in the top surface, and in one aspect can be a multi-lobular or star-shaped aperture, such as those sold under the trademark TORX, or the like, having internal facesdesigned to receive a multi-lobular or star-shaped tool for rotating and driving the shank body. It is foreseen that such an internal tool engagement structuremay take a variety of tool-engaging forms and may include one or more apertures of various shapes, such as a pair of spaced apart apertures or a hex shape designed to receive a hex tool (not shown) of an Allen wrench type. The seat or base surfaceof the drive featurecan be disposed perpendicular to the shank axis, with the drive featureotherwise being coaxial with the axis. In operation, a driving tool is received in the internal drive feature, being seated at the base surfaceand engaging the internal facesof the drive featurefor both driving and rotating the shank bodyinto the vertebra, either before or after the shankis attached to the receiver sub-assembly, with the shank bodybeing driven into the vertebra with the driving tool extending into the receiver.

20 46 21 20 46 47 20 48 26 27 46 40 22 46 20 40 40 In one aspect the shankcan be cannulated, with a boreextending through the entire length thereof, and centered about the longitudinal axisof the shank. The boreis defined by an inner cylindrical wallof the shankand has a circular opening at the shank tipand an upper opening communicating with the internal driveat the seat surface. The boreis coaxial with the threaded shank bodyand the shank head. The boreprovides a passage through the shankinterior for a length of wire (not shown) inserted into the vertebra prior to the collet insertion of the shank body, the wire providing a guide for insertion of the shank bodyinto the vertebra. The bore can also provide for a pin to extend therethrough and beyond the shank tip, the pin being associated with a tool to facilitate insertion of the shank body into the vertebra.

40 3 4 2 4 2 9 10 9 6 2 To provide a biologically active interface with the bone, the threaded shank bodymay be coated, perforated, made porous or otherwise treated. The treatment may include, but is not limited to a plasma spray coating or other type of coating of a metal or, for example, a calcium phosphate; or a roughening, perforation or indentation in the shank surface, such as by sputtering, sand blasting or acid etching, that allows for bony ingrowth or ongrowth. Certain metal coatings act as a scaffold for bone ingrowth. Bio-ceramic calcium phosphate coatings include, but are not limited to: alpha-tri-calcium phosphate and beta-tri-calcium phosphate (Ca(PO), tetra-calcium phosphate (CaPO), amorphous calcium phosphate and hydroxyapatite (Ca(PO)(OH)). Coating with hydroxyapatite, for example, is desirable as hydroxyapatite is chemically similar to bone with respect to mineral content and has been identified as being bioactive and thus not only supportive of bone ingrowth, but actively taking part in bone bonding.

4 7 FIGS.- 1 FIG. 47 48 FIGS.- 100 10 100 101 21 20 100 20 100 22 20 101 21 Illustrated inis the receiverof the pivotal bone anchor assemblyhaving a generally U-shaped appearance with a partially discontinuous substantially cylindrical inner profile and a partially-cylindrical and partially-faceted outer profile, although other profiles are contemplated. The receiveralso has a longitudinal axis, or axis of rotation, that is shown inas being aligned with the longitudinal axisof the shank, such orientation being desirable, but not required during assembly of the receiverwith the shank. After the receiveris pivotally attached to the shank head, either before or after the shankis implanted in a vertebra, the receiver axisis typically disposed at an angle with respect to the shank axisas shown, for example, in.

100 134 104 106 104 70 104 110 114 102 104 103 100 106 134 136 139 100 114 112 113 112 113 106 102 104 50 15 18 FIGS.- The receiverincludes a substantially cylindrical baseintegral with a pair of opposed upright armsforming an upwardly open channelbetween the armsfor receiving the elongate rod. Each of the receiver armshas an interior facethat includes a discontinuous upper portion of a generally cylindrical axial or central borethat extends from the top surfacesof the upright armsat the proximal endof the receiver, downwardly through the open channeland the baseto a bottom openingat the distal endof the receiver. The channel portion or upper discontinuous portion of the central boreis bounded on either side by opposing parallel planar surfacesthat curve downwardly into U-shaped lower saddle surfaces, with the upper opposing planar surfacesand lower saddle surfacedefining the front and back ends of the upwardly open U-shaped channel. In one aspect of the present disclosure the receiver can include breakoff extensions (not shown) extending upwardly from the top surfacesof the upright arms, and which can be threaded for threadable engagement with the outer threads of the closure().

114 116 110 106 102 104 116 50 116 50 104 50 70 116 104 50 104 15 18 FIGS.- The upper discontinuous portion of the cylindrical central borefurther includes a partial helically wound guide and advancement structureextending radially inwardly from the interior faceof the channeland located adjacent the top surfacesof the arms. In the illustrated embodiment, the guide and advancement structureis a partial helically wound interlocking flangeform configured to mate under rotation with a similar structure on the closure(), as described more fully below. However, it is foreseen that the guide and advancement structurecould alternatively be a square-shaped thread, a buttress thread, a modified buttress thread, a reverse angle thread or other thread-like or non-thread-like helically wound discontinuous advancement structure for operably guiding under rotation and advancing the closuredownward between the arms, as well as eventual torquing when the closureabuts against the elongate rod. Additionally, the various structures and surfaces forming the guide and advancement structurecan be configured to resist, to inhibit, to limit, or to preferentially control the splay of the upright armsunder the rotation and advancing the closuredownward between the arms.

114 116 118 116 128 126 118 120 116 122 120 126 120 122 The upper discontinuous portion of the cylindrical central boreimmediately below the guide and advancement structureis defined by a discontinuous cylindrical surfacethat extends downward from the guide and advancement structureto an expansion chamber portionof the receiver cavity. Formed into the discontinuous cylindrical surfaceis an upper “shipping state” groovespaced below the guide and advancement structure, and a lower “capture/locking state” groovelocated between the upper grooveand the receiver cavity. In one aspect the upper groovemay be deeper and wider than the lower groove.

106 100 134 126 128 132 136 128 125 118 130 127 125 113 106 130 127 118 128 130 130 128 132 132 134 Communicating with and located beneath the channelof the receiverat the base portionthereof is the cavityhaving an upper expansion chamber portionand a lower seating surface portionlocated proximate the bottom opening. The expansion chamberis generally defined by an upper discontinuous downwardly-facing annular step surfacedemarking the bottom of the discontinuous cylindrical surface, a lower transition surface, and a substantially cylindrical sidewall surfaceextending between the upper step surfaceor the U-shaped saddle surfacesof the channeland the lower transition surface. The diameter of the cylindrical sidewall surfaceis generally greater than the diameter of the discontinuous cylindrical surfaceimmediately above the upper expansion chamber portion. Furthermore, the lower transition surfacemay have a downwardly and inwardly tapered, or frusto-conical, profile, or an inwardly curved profile, or similar. The lower transition surfaceis generally not intended to be engaged by the collet insert during assembly and use, and serves primarily as a transition structure between the upper expansion chamber portionand the partial spherical interior seating surfacewhile providing material strength for supporting the partial spherical interior seating surfacerelative to the upper portion of the receiver base.

132 126 128 13 126 132 100 170 150 150 170 8 12 FIGS.- The lower seating surface portionof the cavityis spaced below the expansion chamberby the frusto-conical transition surface, and can be a continuous partial spherical seating surface extending 360 degrees around the lower circumference of the receiver cavity. As described in detail below, the partial spherical seating surfaceof the receiveris configured for frictional engagement with a plurality of outer partial spherical surfaces of the distal tip sectionsof a collet insert() when a downwardly directed pressure is applied to a shank head that is captured within the collet insert, as well as for releasing the engagement with the distal tip sectionswhen the pressure is removed.

132 135 136 126 138 134 135 101 100 150 22 150 22 126 136 100 Immediately below the seating surfaceis a lowermost cylindrical surfacethat generally defines the bottom openingthat communicates with both the internal cavityand a receiver lower exterior or bottomof the base. The cylindrical surfaceis substantially coaxially aligned with respect to the longitudinal axisof the receiver, and is also sized and shaped to be smaller than the distal tip sections of the collet insertwhen the shank headis captured within the collet insert, so as to form a restriction to prevent the shank headfrom passing downward through the cavityand out the bottom openingof the receiverduring the use of the pivotal bone anchor assembly.

108 100 100 140 134 106 104 102 142 107 102 134 140 144 140 140 108 100 142 144 100 150 190 100 14 14 20 40 10 70 50 3 7 FIGS.- As noted above, the outer surfaceof the receivercan have a partially-cylindrical and partially-faceted outer profile. In the embodiment of the receiverillustrated in, the faceted or planar portions can include front and back outer planar faceson the receiver basebelow the open channeland extending upward along the side edges of the upright armsto the top surfacesof the arms. In addition, a pair of tool receiving and engaging recessescan be formed into the side outer facesbetween each top surfaceand the receiver base, and can have recessed surfaces that are perpendicular with the front and back outer planar faces. In one aspect additional front and back tool receiving and engaging recessescan be formed into the upper arm portions of the front and back outer planar faces. The faceted or planar portionsof the outer surfaceof the receiverand the tool receiving and engaging recesses,can serve together as outer tool engagement surfaces that allow for tooling to securely engage and hold the receiverduring an initial pre-assembly with the separate collet insertand pressure ringinto the receiverto form the receiver sub-assembly, as well as during coupling of the receiver sub-assemblyto the shankafter or before the implantation of the shank bodyinto a vertebra, and during further assembly of the assemblywith the elongate rodand the closure.

106 100 1 4 7 FIGS.and- Although the rod channelis shown as being an upwardly-open channel in the embodiment of the bone anchor receivershown in, it will be appreciated by one of skill in the art that in other embodiments the receiver may be a closed top receiver, with the rod channel becoming a rod aperture, and in which the elongate rod is introduced into the receiver from the side rather than from the top. This feature may be especially useful when implanting a long series of pivotal bone anchor assemblies along a patient's spine, and it is determined that it would be beneficial to use a closed top receiver at one end to better secure the elongate rod at the beginning of the series.

100 142 144 104 107 100 140 134 It is foreseen, moreover, that other shapes and configurations for the interior and exterior surfaces of the receiver, different from those shown in the drawings while providing for similar interaction and functionality of the various components of the pivotal bone anchor assembly, are also possible and considered to fall within the scope of the present disclosure. For example, the tool receiving and engaging recesses,may be replaced by horizontally-extending “top notch” type tool receiving grooves formed around the upper periphery of the receiver arms, or additional planar faces formed into the side outer surfacesof the receiver(which may or may not be orthogonal to the front and back outer planar faceson the receiver base) are also possible. Additional tool engaging structures or recesses can also be formed on the outer faces of breakoff extensions described above.

8 12 FIGS.- 13 14 FIGS.- 150 160 164 154 160 156 106 150 100 154 151 182 180 160 154 151 153 154 169 169 156 160 24 22 164 169 Illustrated inis the collet inserthaving a lower, generally tubular collet portionthat defines an expandable internal chamber or collet pocket, with integral insert armsprojecting upwardly or proximally from the collet portionto define an insert channelthat is alignable with the receiver channelupon installation of the collet insertinto the receiver. The interior surfaces of the insert armsinclude opposed parallel planar surfacesthat curve downwardly into U-shaped upper surfacesof opposed radial extensionsthat project radially outward from the tubular collet portionbetween the insert upright arms. The opposed parallel planar surfacesare located on either side of a discontinuous upper cylindrical surfaceformed into the interior center portion of the insert armsto define a central tool receiving aperture. The central tool receiving apertureextends vertically downward through the collet insert channeland the upper end of the collet portion(and through the central aperture of the pressure ring ()) to allow passage for a driving tool to engage the internal drive featureor drive socket formed into the top of a shank headthat is captured within the collet pocket. As illustrated in the drawings, the central tool receiving aperturecan be smooth and non-threaded.

154 151 70 154 160 152 70 156 106 153 154 155 152 154 155 155 44 45 FIGS.- The insert armshave a width between the opposed parallel planar surfacesfor operably snugly receiving the elongate rod. Furthermore, the insert armsextend upwardly from the collet portionto top surfacesthat, in one aspect, are spaced below a top surface of an elongate rodwhen the rod is positioned in the insert and receiver channels,(see). The discontinuous upper cylindrical surfaceof the insert armsfurther includes an internal tool engagement structure or recessesformed therein that are spaced below the top surfacesof the insert arms. For purposes described in more detail below, the internal tool engagement structureis configured for engagement with tooling, such as an extraction tool or a deployment tool (not shown). Although shown as a recesswith smooth surfaces, in other embodiments the upper tool engagement structure could be threaded, with the tooling also being threaded at a distal end thereof.

157 155 158 120 122 110 104 159 157 152 158 150 100 150 114 Protruding radially outwardly from the outer side surfacesof the insert armsare opposed lateral ridgesthat are configured for “snap-in” engagement with the upper groovesand with the lower groovesformed into the interior facesof the receiver upright armswhen the receiver sub-assembly is in a pre-assembled shipping state position or the capture/locking state position, respectively. The protruding lateral ridges are non-threaded, and in one aspect a small rounded relief groovecan be formed at the junction between the vertical outer side surfacesof the collet insert armsand the top surfaces of the opposed lateral ridges, for reasons described in more detail below. It is foreseen that the arrangement of protruding ridges and recesses on the collet insertand the receiver, respectively, can be reversed, with the shipping and locking recesses being formed into the exterior or outer surface of the collet insertand the internal ridges protruding inwardly from the receiver central bore. Other combinations of ridges and grooves, or entirely different structures, including but not limited to ratchets, a separate snap ring, and the like, are also possible.

150 180 160 154 185 180 186 112 104 156 106 180 186 150 114 8 12 FIGS.- In the embodiment of the collet insertillustrated in, the opposed radial extensionsproject radially outward from the tubular collet portionbetween the insert upright armsto end surfaces, and can serve to perform a number of useful functions. For example, the radial extensionscan include substantially planar side edge surfacesthat are configured to slidably engage with the upper opposing planar surfacesof the receiver upright arms, so as to align the open insert channelwith the open receiver channel. The radial extensionscan also include top edge surfacesthat are substantially planar or flat, and which can be configured to at least partially receive the deployment tooling (not shown) used to drive the collet insertdownward within the receiver central boreduring deployment from the pre-assembled shipping state position to the capture/locking state position, as described below.

182 180 70 92 70 182 180 70 100 190 182 180 The upper surfacesof the radial extensionscan also be curved to match the underside of the elongate rod. However, it will be appreciated that the underside surfacesof the elongate rodgenerally do not contact the upper surfacesof the radial extensions, in order to restrict or prevent the creation of an alternative load path from the elongate roddown into the receiver bodyother than the load path defined by the pressure ring. Thus, the upper surfacesof the radial extensionsmay be shaped to match the curvature of the elongate rod so as to provide increased and uniform spacing between the two curved surfaces, so as to better avoid accidental contact during assembly and use.

188 180 113 104 188 180 113 150 100 158 170 188 113 170 132 126 180 Similarly, the lower or underside surfacesof the radial extensionscan also be curved to match with the curved saddle surfacesextending between the receiver upright arms, thereby allowing for an increased range of vertical movement between the two surfaces. Generally, the curved underside surfacesof the radial extensionsare maintained in a position that is spaced above the curved saddle surfaces, in order to restrict or prevent the creation of an alternative load path between the collet insertand the receiver bodyother than the load path defined by the opposed lateral ridgesand the distal tips sections, as described in detail below. Alternatively, it is contemplated that the curved underside surfacescan be configured to engage with the curved saddle surfaceas an indexing surface, so as to align the distal tip sectionswith the partial spherical seating surfaceof the receiver cavity, and/or to provide additional support for the radial extensions.

160 162 163 164 190 22 164 161 153 154 161 166 162 160 168 166 167 168 22 190 As noted above, the collet portionhas a generally tubular construction with substantially cylindrical sidewallshaving inner surfacesdefining an expandable internal chamber or collet pocketfor receiving and engaging both the pressure ringand the shank head. The proximal or upper portion of the collet pocketis defined by a discontinuous, downward-facing stop surface or shelf surfacethat extends radially outward below the discontinuous upper cylindrical surface, and which serves as the internal bottom surface of the upright insert arms. Moving downward from the downwardly-facing stop surface, a plurality of longitudinal slotsare formed through the sidewallsof the collet portionthat sub-divide the collet portion into a plurality of resilient collet fingers. The upper ends of the slotscan terminate in rounded stress-relieving apertures, including but not limited to circular and oval shapes. The resilient collet fingersare configured to maintain their downward orientation except when deflected outwardly by the passage of the shank heador pressure ring, as described in detail below.

170 168 179 164 176 22 190 170 172 32 22 30 170 174 132 126 168 150 172 178 170 175 164 172 175 173 176 173 173 172 178 170 Distal tip sectionscurve inwardly at the lower ends of the resilient collet fingersto partially close the distal endof the expandable collet pocketand to define an expandable distal pocket openingthat returns to its nominal shape after deflection by the passage of the shank heador pressure ring. The inner portions of the distal tip sectionsdefine a plurality of inner partial spherical surfacesthat engage the spherical outer surfaceof the shank headbelow the hemisphere plane. The outer portions of the distal tip sectionsdefine a plurality of outer partial spherical surfacesthat are configured to engage the partial spherical interior seating surfaceof the receiver cavity, generally without contraction or inward displacement of the collet fingers, when the collet insertis in the capture/locking state position. Extending between the inner partial spherical surfacesand the bottom surfacesof the distal tip sectionsare chamfered surfacesthat can engage the upper outer edge of the pressure ring or the spherical outer surface of the shank head to facilitate the uploading of the pressure ring and shank head, respectively, into the expandable collet pocket. In addition, the junction between the inner partial spherical surfacesand the chamfered surfacesform a plurality of innermost edgesthat together define the size of the distal pocket opening. If desired, the innermost edgesand chamfered surfacecan be rounded together to form rounded innermost edges that are continuously curved between the inner partial spherical surfacesand the bottom surfacesof the distal tip sections.

170 162 160 170 174 132 22 As can be seen in the drawings, the distal tip sectionscan have a thickness that is greater than the thickness of the tubular sidewallsof the collet portion, so that each of the distal tip sections has a bulbous profile. In one aspect the thickness of the distal tip sectionscan be varied or controlled so as to better position their outer partial spherical surfacesrelative to the partial spherical interior seating surface, as well as to provide increased metallic material to support against pullout of the shank headduring assembly and use.

It is foreseen that other shapes and configurations for the interior and exterior surfaces of the collet insert, different from those shown in the drawings while providing for similar interaction and functionality of the various components of the pivotal bone anchor assembly, are also possible and considered to fall within the scope of the present disclosure. For example, the collet insert can be positioned within the receiver in different ways, such as being rotated in place, crimped in place, or snapped in place using different structures other than those shown in the drawings of the present disclosure, etc.

158 122 158 150 118 114 In particular, it is contemplated that the opposed radial extensions may be removed or eliminated from the collet insert, and that the collet insert can be configured for downloading into the receiver open channel with the protruding lateral ridges aligned with the receiver channel, and then rotated or twisted into position with the protruding lateral ridges engaged within the upper shipping state groove and the open insert channel coming into alignment with the open receiver channel. The amount of rotation can be about 90 degrees. In some embodiments the collet insert can be prevented from further rotation within the receiver by using crimps, a blocking tab or stop structure, and the like. It will be appreciated that the “Twist-In-Place” embodiment of the collet insert can still include downward tool deployment of the collet insert to the capture/locking state position, with the opposed lateral ridgesbeing snapped into the lower capture/locking state groovefollowing a sliding biased engagement between the opposed lateral ridgesof the collet insertand the discontinuous cylindrical surfacesof the receiver central bore.

Additional details and disclosure regarding deployment tools or tooling for preparing, assembling, and/or deploying bone screws and pivotal bone anchor assemblies or components thereof during spinal surgery, including a receiver sub-assembly having an insert with “Twist-In-Place” and downward tool deployment features similar to those described in the alternative above, can be found in co-pending Patent Cooperation Treaty (PCT) Application PCT/US 2019/51190, filed Sep. 13, 2019, and claiming the benefit of U.S. Provisional Application No. 62/731,059, filed Sep. 13, 2018, with each of the above-referenced applications being incorporated by reference in its entirety herein and for all purposes.

13 14 FIGS.- 190 70 32 22 190 192 198 194 164 194 162 168 164 190 164 190 164 195 194 192 190 160 150 Illustrated inis the pressure ringthat is configured to transfer a downwardly-directed force from the elongate rodto the spherical outer surfaceof the shank head. The pressure ringgenerally has a ring shaped body with an annular top surface, an annular bottom edge surface, and a substantially-cylindrical outer surfacethat can be sized and shaped for slidable interference engagement with the interior sidewall surfaces of the collet pocket. For example, the diameter of the cylindrical outer surfacecan be equal to or slightly greater than the inner diameter of the tubular sidewallsand resilient collet fingersthat define the collet pocket, so as to provide a slight interference engagement when the pressure ringis positioned in the upper portion of the collet pocket, with the slight interference engagement being sufficient to hold or maintain the pressure ringwithin the collet pocketin the shipping state position. In one aspect the outer surface may further include an upper tapered or relief portionabove the cylindrical outer surface portionthat limits the interference engagement to a narrow cylindrical interference region spaced below the top surfaceof the pressure ring, and which can further facilitate the uploading and positioning of the pressure ring into the collet portionof the collet insert.

192 190 74 70 156 192 190 164 199 192 24 164 199 195 192 161 150 190 150 The top surfaceof the pressure ringis configured to engage the bottom or lowermost or underside surfaceof the elongate rodwhen the elongate rod is positioned within the collet insert channel. As shown in the drawings, the top surfacecan be a symmetrical substantially-planar annular surface, having a symmetrical shape that allows for uploading the pressure ringinto the collet pocketin any rotational orientation. A central tool receiving apertureis formed through the top surfaceto allow passage of a driving tool to engage the shank head tool engagement structureor drive socket that is captured within the collet pocket, and which central aperture, in one aspect, can be defined by a cylindrical inner surfacethat is smooth and non-threaded. As discussed below, outer edge portions of the top surfacecan abut the discontinuous downwardly-facing stop surfaceof the collet insertwhen the pressure ringis uploaded into the shipping state configuration within the collet insert.

195 198 190 196 32 22 196 32 Extending between the cylindrical inner surfaceand the annular bottom edge surfaceof the pressure ringis an inner or lower, downwardly-opening concave surfacethat is configured to receive and mate with the spherical outer surfaceof the shank head. The lower concave surfacecan be textured, ridged, coated, and the like, to improve the frictional engagement with the spherical outer surface.

190 It is foreseen that other shapes and configurations for the pressure ring, different from those shown in the drawings while providing for similar interaction and functionality, are also possible and considered to fall within the scope of the present disclosure. For example, it is contemplated that alternative embodiments of the pressure ring can be slotted, can have a snap fitment with the collet insert, can have outer threads that mate with the collet insert, can include an alignment feature or structure that engages with a complementary structure in the collet insert, or can have a curved or channeled top surface that is alignable with the insert channel, and the like.

190 164 150 158 150 120 100 As described in more detail below, the pressure ringis generally uploaded into the expandable collet pocketafter the collet inserthas been downloaded into its shipping state position, with the opposed lateral ridgesof the collet insertengaged within the upper groovesof the receiver. It is nevertheless foreseen that the pressure ring may be uploaded into the collet pocket prior to pre-assembly, and then downloaded together with the collet insert into the shipping state position.

15 18 FIGS.- 50 52 56 60 54 116 110 104 60 116 50 104 104 50 106 60 116 With particular reference to, the closurecomprises a generally cylindrical closure body having a top surface, a bottom surface, and an outer continuous guide and advancement structureformed into the outer side surfaceof the closure body that operably joins with the guide and advancement structureformed into the interior faceof the receiver arms. In one aspect the guide and advancement structures,can be helically wound flanges with splay-resisting or splay-controlling flange profiles for operably guiding under rotation and advancing the closure structuredownward between the armsand having such a nature as to resist or control the splaying of the armswhen the closure structureis advanced into the receiver channel. In other aspects the guide and advancement structures,may take on a variety of alternative forms, including but not limited to a buttress thread, a square thread, a reverse angle thread, or other thread like or non-thread like helically wound advancement structure.

56 58 56 As shown in the drawings, in one aspect the bottom surfaceof the closure can include a downwardly-projecting central projectionfor engaging and securing the elongate rod, and for controlling the closure torque to thrust ratio. In other embodiments the bottom surface can include an annular projection, a point ring (i.e., an annular ring surrounding a central point or projection), a recessed surface surrounded by a low outer ridge, and the like. In yet other embodiments the bottom surfacecan be substantially planar across the extent thereof.

52 50 66 50 66 66 50 52 68 50 66 67 66 66 The top surfaceof the closurecan further include a driving tool engagement structure, such as internal drive socket, which extends downward or inward into the body of the closure. The internal drive socketcan be used for closure installation or removal. Similar to the internal drive socket formed into the shank head, the internal socketof the illustrated closureis an aperture formed in the top surface, and in one aspect can be a multi-lobular or star-shaped aperture, such as those sold under the trademark TORX, or the like, having internal facesdesigned to receiver to a multi-lobular or star-shaped tool for rotating and driving the closure. It is foreseen that such an internal tool engagement structuremay take a variety of tool-engaging forms and may include one or more apertures of various shapes, such as a pair of spaced apart apertures or a hex shape designed to receive a hex tool (not shown) of an Allen wrench type. The seat or base surfaceof the drive featureis disposed perpendicular to a closure axis, with the drive featureotherwise being coaxial with the axis.

104 100 In another aspect of the present disclosure, a break-off extension (not shown) can be attached the upper end or top surface of the closure, and extend upwardly away therefrom to provide an external tool engagement structure that can be used for rotatably advancing the closure downward between the armsof the receiver. In one aspect the break-off extension can be designed to allow the extension to break from the closure at a preselected torque, for example, 60 to 140 inch pounds. It is further foreseen that closures having other shapes, configurations, thread forms or non-threaded engagement alternatives, and the like, that are different from those shown in the drawings while providing for similar interaction and functionality of the various components of the pivotal bone anchor assembly, are also possible and considered to fall within the scope of the present disclosure.

19 FIG. 29 48 FIGS.- 100 150 190 14 14 With reference to, the receiver, the collet insert, and the pressure ringform the components of a receiver sub-assembly, and are generally pre-assembled together at a factory setting that includes tooling for holding, alignment and manipulation of the component pieces. In some circumstances, the shank is also assembled with the receiver sub-assemblyat the factory. In other instances, it is desirable to first implant the shank, followed by addition of the pre-assembled receiver sub-assembly at the insertion point (see, e.g.,). In this way, the surgeon may advantageously and more easily implant and manipulate a number of shanks along the patient's spine, distract or compress the vertebrae with the shanks, and work around the shank upper portions or shank heads without the cooperating receivers being in the way. In other instances, it is desirable for the surgical staff to pre-assemble a shank of a desired size and/or variety (e.g., cannulated shank body, different thread patterns on the shank body, and/or hydroxyapatite on the shank body), with the receiver sub-assembly prior to implantation of the shank into a patient's vertebra. Allowing the surgeon to choose the appropriately sized, type, or treated shank advantageously reduces inventory requirements, thus reducing overall cost.

100 150 190 14 180 150 106 150 114 100 158 120 154 150 158 116 100 104 106 150 19 FIG. 20 28 FIGS.- 20 21 26 FIGS.-and 20 FIG. 21 26 FIGS., The pre-assembly of the receiver, the collet insert, and the pressure ringcomponents ofinto a receiver sub-assemblyis shown in. With particular reference to, first the opposed radial extensionsof the collet insertare aligned with the rod channelof the receiver, and then the collet insertis dropped or driven downward into the central boreof the receiver() until the opposed lateral ridgesor projections become engaged within the receiver upper shipping state grooves(). In one aspect tooling (not shown) may be used to pinch inward the insert upright armsas the collet insertis dropped downwardly into position, so as to allow the collet insert lateral ridgesto pass downward through the guide and advancement structureof the receiverwithout significant interference between the parts. Alternatively, tooling (not shown) may be used to press open the receiver armsand expand the receiver channelas the collet insertis dropped downwardly into position, also to allow the insert lateral ridges to pass downward through the receiver guide and advancement structure.

21 FIG. 150 180 112 104 114 158 120 170 168 128 126 With continued reference to, during the downloading of the collet insertto the shipping state position, the insert opposed radial extensionscan become slidably engaged by the upper opposing planar surfacesof the receiver upright armsto prevent the collet insert from rotating within the receiver axial bore. In addition, with the exterior projecting ridgesbecoming engaged within the receiver upper shipping state grooves, the distal tip sectionsof the resilient collet fingersare suspended and centralized within the upper expansion chamber portionof the receiver cavity.

22 23 FIGS.- 190 136 176 168 176 128 173 170 194 190 With reference to, the pressure ringcan now be uploaded through the receiver bottom openingand into the collet insert distal pocket opening, causing the collet fingersto flex outwardly and the distal pocket openingto expand within the expansion chamberwhile the innermost edgesof the distal tip sectionsslide against the cylindrical outer surfaceof the pressure ring.

24 25 FIGS.- 190 164 192 190 161 150 192 190 184 180 150 164 166 167 168 192 161 14 With reference to, the pressure ringcan continue upward through the collet pocketuntil it reaches the shipping state configuration, in which the annular top surfaceof the pressure ringabuts the discontinuous downwardly-facing stop surfaceof the collet insert. In this position the top surfaceof the pressure ringcan also be substantially flush with the planar top edge surfacesof the radial extensions. In one aspect the enclosed pressure ringcan be pressed into a slight interference engagement in its position within the upper portion of the collet pocket, in a location that is at least partially above the longitudinal slotsand/or relief aperturesthat define the resilient collet fingers. With the top surfaceof the pressure ring abutting the downwardly-facing stop surface, the pre-assembly of the receiver sub-assemblyis complete.

24 25 27 FIGS.-and 24 FIG. 24 25 27 FIGS.-and 14 150 114 158 120 120 150 100 150 180 112 104 190 164 194 190 163 162 As shown in, the receiver sub-assemblyis in a shipping state configuration in which the collet insertis held in a vertical position within the receiver central axial boreand inhibited from vertical movement due to the overlapped (or overlapping) engagement of the opposed lateral ridgesbeing received within the upper shipping state grooves. Furthermore, the upper shipping state groovesare sized and shaped to prevent any upward movement of the collet insertrelative to the receiver, while allowing for downward movement or deployment of the collet insertonly with considerable direct force that may be provided by the appropriate tooling. As shown in, the collet insert is also held or ‘clocked’ in angular position by the opposed radial extensionsthat are positioned between the upper opposing planar surfacesof the receiver upright arms. As noted above, the pressure insertmay also be held or secured within the upper continuous cylindrical portion of the collet pocketwith a slight interference engagement, or some other type of engagement, between the cylindrical outer surfaceof the pressure ringand the inner surfaceof the tubular sidewall. In one aspect the shipping state configuration shown inmay also be known as the collet insert/pressure ring pre-deployment configuration.

28 FIG. 170 168 128 126 136 174 170 132 136 132 174 170 168 150 Furthermore, and with additional reference to, the distal tip sectionsof the resilient collet fingers, acting as a retainer, will be suspended and centralized within the upper expansion chamber portionof the receiver cavityand spaced above the receiver bottom opening, in preparation for receiving the spherical head of the bone anchor. The outer partial spherical surfacesof the distal tip sectionsare also positioned vertically above the partial spherical interior seating surfacethat is located just above the receiver bottom opening. As discussed below, the inner diameter of the partial spherical interior seating surfacecan be equal to or greater than the outer diameter of the outer partial spherical surfacesof the distal tip sections, so that the distal tip sections (and resilient collet fingers) can be maintained in a neutral position or in a slightly expanded position when the collet insertis in a lower “capture/locking state” position.

29 43 FIGS.- 29 FIG. 14 10 22 20 14 22 136 32 22 Illustrated inis the assembly or coupling of the pre-assembled receiver sub-assemblyof the pivotal bone anchor assemblyof the present disclosure to the headof a shank or bone anchor. As shown in, the receiver sub-assemblyis first positioned above the shank headwith the receiver bottom openinggenerally aligned with the spherical outer surfaceof the shank head.

30 31 FIGS.- 14 20 22 136 32 173 170 173 175 170 32 With reference to, the receiver sub-assemblyis then dropped downward (or the shankis moved upward, depending on the frame of reference of the reader) until the shank headenters the bottom openingand the upper portion of the spherical outer surfacecontacts the innermost edgesof the distal tip sections. As previously described, the innermost edgesor chamfered surfaceof the distal tip sectionscan be rounded or chamfered to facilitate slidable engagement with the spherical outer surface.

32 33 FIGS.- 14 20 22 173 170 168 176 128 126 With reference to, the receiver sub-assemblycontinues to move downward (or the shankmoves upward) as the upper portion of the shank head spherical outer surfacebears against the innermost edgesof the distal tip sections, causing the collet fingersto flex outward and the distal pocket openingto expand within the upper expansion chamber portionof the receiver cavity, until the distal pocket opening reaches maximum expansion.

34 35 FIGS.- 14 20 22 32 196 190 32 163 163 164 With reference to, the receiver sub-assemblycontinues to move downward (or the shankmoves upward) until the shank headreaches max push-through, in which the upper portion of the spherical outer surfaceabuts the lower concave surfaceof the pressure ringand a center portion of the spherical outer surfacebears against the inner surfacesof the substantially cylindrical sidewallsthat define the collet pocket.

36 37 FIGS.- 14 20 32 22 172 170 168 20 100 150 100 22 164 150 14 20 166 22 164 With reference to, the receiver sub-assemblyis moved or pulled back upward (or the shankdownward) until the lower portion of the spherical outer surfaceof the shank headcontacts the plurality of inner partial spherical surfacesof the distal tip sections. In one aspect the collet fingerscan be slightly expanded compared to their nominal state so as to provide a light friction fit or head drag between the shankand receiver, prior to the collet insertbeing downwardly deployed within the receiver. The shank headis now lightly captured within the pocketof the collet insert, but could still be removed from the receiver sub-assemblyif the shankwere to be pulled forcefully downward, causing the resilient collet fingersto expand and release the shank headfrom the collet pocket.

38 39 FIGS.- 150 190 22 184 180 184 158 150 20 100 118 114 158 154 150 156 150 70 156 190 193 154 150 158 120 100 155 153 154 150 With reference to, the collet insert, together with the enclosed pressure ringand lightly captured shank head, can then be pushed downward with deployment tooling (not shown) that engages the planar top edge surfacesof the opposed radial extensions. The pushing or deployment can include the application of considerable force to the top of the collet insert tool engagement surfaces, so as to push the opposed lateral ridgesof the collet insertdownward out of the upper shipping state groovesof the receiverand onto the discontinuous cylindrical surfaceof the central bore, where the lateral ridgesencounter an interference fit that resists the downward motion. The force required to overcome this interference fit can be about 200 pounds-force or greater, and is generally provided by the deployment tooling. This action can temporarily cause the upwardly-projecting armsof the collet insertto flex inwardly, temporarily reducing the gap at the top of the collet insert channel. With the collet insertin this position, the elongate rodwould not necessarily fit within the collet insert channel. As described above, the outer surface of the pressure ringcan have an upper tapered relief portionthat is tapered inwardly to provide room for this inward flexing of the upright armsof the collet insert, so as to allow the lateral ridgesto become disengaged from the upper shipping state groovesof the receiver. In an alternative embodiment, the deployment tooling (not shown) can also or preferably engage the upper tool engagement structure (e.g., recess) formed into the discontinuous upper cylindrical surfaceof the integral upright armsextending above the collet portion of the collet insert.

40 41 FIGS.- 150 190 158 122 114 132 174 170 170 172 170 32 22 22 136 22 114 With reference to, the collet insertwith the enclosed pressure ringcan continue to be pushed or deployed downward with the deployment tooling until (a) the opposed lateral ridgessnap into the lower “capture/locking state” groovesof the receiver central bore, (b) the partial spherical interior seating surfaceengages the plurality of outer partial spherical surfacesof the distal tip sectionsto restrain further outward movement or flexing of the distal tip sections, and (c) the plurality of inner partial spherical surfacesof the distal tip sectionsmore forcefully engage the lower portion of the spherical outer surfaceof the shank headto prevent the shank headfrom exiting downward through the receiver bottom opening. The shank headis now fully captured within the receiver sub-assemblywith the collet insert in the capture/locking state position.

150 174 170 126 132 132 174 170 168 150 40 41 FIGS.- During the downward deployment of the collet insertto the capture/locking state position shown in, the outer partial spherical surfacesof the distal tip sectionsmay descend vertically through the receiver internal cavityuntil engaging with and seating upon the partial spherical interior seating surface. As noted above, the inner diameter of the partial spherical interior seating surfacecan be equal to or slightly greater than the outer diameter of the outer partial spherical surfacesof the distal tip sections, so that distal tip sections(and the resilient collet fingers) can be maintained in a neutral position or in a slightly expanded position when the collet insertis in the lower capture/locking state position.

132 126 174 170 172 170 32 20 In addition, it will be appreciated that the partial spherical interior seating surfaceof the receiver cavity, the outer partial spherical surfacesof the distal tip sections, the inner partial spherical surfacesof the distal tip sections, and the spherical outer surfaceof the shank headcan, in one aspect, define four substantially-concentric spherical surfaces (i.e. when their geometric centers are located at substantially the same location along the receiver longitudinal axis). Alternatively, it is also contemplated that the geometric centers of one or more of the spherical surfaces (e.g., the receiver partial spherical seating surface) can be vertically offset from the other geometric centers to facilitate the separation of the surfaces during remobilization, as described in more detail below. It is further foreseen that other diameters and/or configurations for the partial spherical surfaces and their geometric centers are also possible.

42 43 46 FIGS.-and 190 164 196 32 22 194 190 163 64 106 156 42 43 46 With reference to, the enclosed pressure ringcan now be individually pushed or deployed downwardly from its position in the upper portion of the collet pocketuntil the lower, downwardly-opening concave surfaceof the pressure ring engages the upper portion of the spherical outer surfaceof the shank head. A downwardly-directed force sufficient to overcome the slight interference engagement between the cylindrical outer surfaceof the pressure ringand the tubular sidewall inner surfacesof the collet pocketmay be required. The downwardly-directed force can be directly applied with a tool or by the elongate rod positioned in the receiver and insert channels,prior to deployment. In one aspect the capture/locking state configuration shown in-andmay also be known as the collet insert/pressure ring post-deployment configuration.

22 190 22 32 132 126 194 190 163 164 14 22 14 20 100 22 106 100 22 106 Optionally, once engaged with the shank head, the pressure ringmay be further compressed downward onto the shank headby a deployment tool, so as to apply an initial loading onto the spherical outer surfacethat is transferred downward to the partial spherical seating surfaceof the receiver cavity. This initial compressive loading may be maintained by a frictional interference fit between the cylindrical outer surfaceof the pressure ringand the sidewall inner surfacesof the collet pocket. In one aspect the compressive loading may also be sufficient to establish, or further assure, a non-floppy friction fit that holds the position of the receiver sub-assemblyrelative to the shank head, while still allowing for movement of the receiver sub-assemblyrelative to the bone anchorwith an applied force. For example, the friction fit can allow for rotation of the receiveraround the shank head, with an applied twisting force, so as to align the receiver channelwith the receiver channels of one or more adjacent bone anchor assemblies. The friction fit can also allow for angulation of the receiverrelative the shank head, with an applied moment force, also to align the receiver channelwith the receiver channels of an adjacent bone anchor assembly.

44 45 47 48 FIGS.-and- 10 70 50 14 20 70 156 74 70 192 150 50 114 60 116 110 104 50 56 58 50 72 70 50 70 190 22 170 150 132 10 14 20 Illustrated inis the pivotal bone anchor assemblyas fully assembled and locked with the elongate rodand closure. For instance, after a desired alignment of the receiver sub-assemblyto the bone anchorhas been achieved, the elongate rodcan be installed (i.e., reduced) into the collet insert channeluntil the lowermost or underside surfaceof the elongate rodengages the top surfaceof the pressure ring. The closurecan then be installed into the upper portion of the receiver axial bore, in which the continuous guide and advancement structureof the closure body engages the discontinuous guide and advancement structureformed into the interior faceof the receiver upright arms. The closurecan be threaded downwardly until the bottom surfaceor the protrusionof the closureengages the top surfaceof the elongate rod. Further rotation/torquing of the closurecan then be used to drive the elongate roddownward onto the pressure ring, which in turn drives the shank headand the distal tip sectionsof the collet insertfurther downward into the partial spherical seating surfaceto achieve a final locking of the bone anchor assembly, in which the receiver sub-assemblycan no longer move relative to the bone anchor.

70 150 156 192 190 182 180 70 100 190 22 196 190 32 22 172 170 32 In one aspect the elongate roddoes not push directly on the collet insertafter downloading into the collet insert channel, as the top surfaceof the pressure ringremains above the upper curved surfacesof the opposed insert extensionsto establish a single load path from the elongate roddown into the receiver bodyvia the pressure ring. Thus, the final locked state of the shank headcan be provided from above by frictional engagement between the downwardly-opening concave surfaceof the pressure ringand the upper portion of the spherical outer surfaceof the shank head, and from below by frictional engagement between the plurality of inner partial spherical surfacesof the distal tip sectionsand the lower portion of the spherical outer surface.

52 10 In yet another aspect of the disclosure, a closure break-off extension (not shown) can be configured to shear away from the top surface or endof the closure body at a pre-determined torque value, thereby ensuring that the pivotal bone anchor assemblyis fully locked at a consistent pre-determined torque value.

132 174 170 10 170 150 22 134 170 134 174 170 132 126 170 134 20 168 170 22 178 170 46 FIG. Furthermore, it will be appreciated by one of skill in the art that the interface between the receiver cavity partial spherical seating surfaceand the plurality of outer partial spherical surfacesof the distal tip sectionscan determine the strength, or pull-out resistance, of the fully locked pivotal bone anchor assembly. For example, and with reference back to, the distal tip sectionsof the collet insertare generally configured to transfer load from the shank headto the receiver base. Relative motion between the distal tip sectionsand the receiver baseis limited by friction and interference between the outer surfacesof the distal tip sectionsand the partial spherical seating surfaceof the receiver cavity. Assuming that relative motion between the distal tip sectionsand the receiver baseis restricted or substantially prevented, pull-out resistance of the shank or bone anchoris provided by a plurality of shear walls in the collet fingers/distal tip sectionsthat start at the major diameter of the shank headand terminate at the bottom surfaceof the distal tip sections.

10 10 22 20 10 22 10 190 32 22 14 22 49 51 FIGS.- Among others, one useful aspect of the fully-assembled pivotal bone anchor assemblydisclosed above is that bone anchor assemblycan be re-mobilized relative to the headof the bone anchorsimply by removing or loosening the closure. For example, and with reference to, the closure and elongate can be removed so as to remobilize the pivotal bone anchor assemblyrelative to the shank head. Although the bone anchor assemblyis shown in the drawings with the closure and elongate rod being completely removed, remobilization can be accomplished simply by loosening the closure while leaving both the closure and elongate rod in place. Loosening the closure removes the downward force applied to the pressure ringthrough the elongate rod, thereby reducing the frictional engagement on the upper and lower portions of the spherical outer surfaceof the shank head. With the reduction of the frictional engagement on the upper and lower portions of the spherical outer surface, the receiver sub-assemblybecomes free again to rotate relative to the shank head.

132 174 172 170 22 170 150 132 10 132 126 132 168 132 150 126 132 174 150 100 132 170 132 126 As previously described, the partial spherical profile of the receiver cavity seating surfacecan be substantially concentric with each of the partial spherical profiles of the outer surfacesand inner surfacesof the distal tip sections, and with the spherical profile of the shank head. This design reduces the likelihood for inadvertently creating a permanently locked engagement between the distal tip sectionsof the collet insertand the receiver cavity seating surfacewhen fully locking the pivotal bone anchor assembly, as described and illustrated above. For example, using a partial spherical profile for the seating surfaceof the receiver cavity, rather than a conical or tapered profile, better distributes the friction forces across the seating surface, better centers the collet fingersaround the circumference of the receiver cavity seating surfaceto avoid cocking/misalignment of the collet insertwithin the receiver cavity, avoids creating a concentrated line of contact that may cause localized deformation and bonding between the two surfaces,; and avoids a tapered locking engagement between the collet insertand the receiver. As noted above, the geometric center of the partial spherical profile of the receiver cavity seating surfacecan also be vertically offset or displaced slightly from the geometric centers of the other three spherical profiles. It is contemplated that this vertical displacement can operate to re-direct the normal force to twist the upper portions of the distal tip sectionstoward or away from the partial spherical seating surfaceof the receiver cavity.

52 59 FIGS.- 52 FIG. 53 54 FIGS.- 14 10 22 20 14 80 106 100 150 80 82 84 86 155 153 154 150 84 88 84 89 154 106 100 84 86 153 154 155 84 80 106 100 156 150 156 86 153 Illustrated inis the disassembly and removal of the receiver sub-assemblyof the pivotal bone anchor assemblyfrom the headof the shank or bone anchor. As shown first in, after the removal of the closure and the elongate rod from the receiver sub-assembly, a disassembly toolcan be downwardly introduced into the open channelof the receiverand engaged with the collet insert. The disassembly toolincludes a center portioncomprising two downwardly-extending prongs, with each prong having an outwardly-facing hook portionthat is sized and shaped to engage with the upper tool engagement structures or recessesformed into the discontinuous upper cylindrical surfaceof the insert armsof the collet insert. The prongsmay be configured to flex inwardly toward each other, with the lower tipof each prongincluding a tapered surfacethat first contacts the top edge of an insert upright armwhen introduced into the open channelof the receiver. This initial contact can cause the prongsto flex inwardly toward each other, after which the outwardly-facing hook portionsride downwardly along the discontinuous cylindrical surfacesof the insert armsuntil they snap into the upper tool engagement recesses(). Alternatively, the prongsof the disassembly toolmay be orientated to align with the open channelof the receiverand the open channelof the collet insertbefore being positioned downwardly within the insert channel, and then rotated about the receiver longitudinal axis until the hook portionsengage with the upper tool engagement recesses.

86 80 153 82 80 158 150 122 120 80 100 82 80 100 158 122 118 114 82 80 20 100 122 120 22 150 80 100 82 80 100 22 53 54 FIGS.- 55 56 FIGS.- Once the hook portionsof the disassembly toolare engaged within the upper tool engagement recesses, as shown in, the center portionof the disassembly toolis withdrawn upward to pull the opposed lateral ridgesof the collet insertfrom the lower capture/locking state groovesto the upper shipping state grooves, as shown in. In practice, the disassembly toolcan further include an outer portion (not shown) that engages with and pushes downwardly on the receiverwhile the center portionis withdrawn upwardly. This can include the application of considerable force between the disassembly tooland the receiverto pull the opposed lateral ridgesupward out of the lower groovesand onto the discontinuous cylindrical surfaceof the receiver central bore. For example, in one aspect the force required to overcome this engagement can be about 400 pounds-force or greater, generally provided by the counter-directional movement between the center portionand outer portion of the disassembly tool. In situations where the position of an implanted bone anchoris fixed, this causes the receiverwith its lower capture/locking state groovesand upper shipping state groovesto displace downwardly relative to the shank head, rather than the collet insertto displace upwardly. It will be appreciated that the application of force between the disassembly tooland the receiver, provided by the counter-directional movement between the center portionand outer portion (not shown) of the disassembly tool, can substantially balance the load across the receiverso as to reduce or substantially eliminate the transfer of any disassembly loads or forces to the shank head.

57 58 FIGS.- 59 FIG. 59 FIG. 158 150 120 14 20 80 86 155 150 168 176 128 126 176 80 14 20 22 136 100 14 22 80 14 80 86 155 With reference to, once the opposed lateral ridgesof the collet insertare positioned within the upper shipping state grooves, the entire receiver sub-assemblycan then be pulled upward off the bone anchor or shankby the disassembly toolhaving hook portionsthat are still engaged within the tool engagement recessesof the collet insert, causing the collet fingersto flex outward and the distal pocket openingto expand within the upper expansion chamberof the receiver cavity, until the distal pocket openingexpands sufficiently to allow passage of the shank head. The disassembly toolcan be used to continue pulling the receiver sub-assemblyupward off the bone anchoruntil the shank headexits the bottom openingof the receiver, as shown in. After removal of the receiver sub-assemblyfrom the shank head, in one aspect the disassembly toolcan be disengaged from the receiver sub-assemblyby rotating the disassembly toolabout the receiver longitudinal axis until the hook portionsslide out from the tool engagement recesses(see).

80 100 150 80 150 104 100 It is foreseen that other shapes and configurations for the disassembly tool, the receiverand the collet insert, different from those shown in the drawings while providing for similar interaction and functionality for disassembling the pivotal bone anchor assembly, are also possible and considered to fall within the scope of the present disclosure. For example, it is contemplated that the disassembly toolcan access the collet insertby other routes, such as through apertures in the upright armsof the receiver, and the like.

60 63 FIGS.- 63 FIG. 200 10 214 212 224 222 214 210 216 217 224 222 226 216 With reference to, illustrated therein is another representative embodimentof the pivotal bone anchor assembly that is substantially similar to the pivotal bone anchor assemblydescribed above, except for modifications to the interface between the partial spherical seating surfaceof the receiver cavity, and to the outer partial spherical surfacesof the distal tip sections. In particular, the partial spherical seating surfaceof the receivercan be modified to include an inwardly-projecting ridgehaving a horizontal top surface. In addition, the outer partial spherical surfacesof the distal tip sectionscan be modified to include a complementary notchthat is sized and shaped to receive the ridgein the capture/locking state position, as shown in.

22 204 214 216 224 222 100 222 220 22 211 222 211 224 222 214 212 227 226 217 216 210 220 210 222 211 20 221 222 222 228 222 It is contemplated that the above-referenced modifications, which serve to establish a seating interface with a ridged surface, may modify or improve the resistance to pull-out of the shank headfrom the receiver sub-assemblyduring assembly, loading, and use. For instance, and similar to the pull-out analysis described above, the interface between the receiver partial spherical seating surfacewith the inwardly-projecting ridgeand the plurality of outer partial spherical surfacesof the distal tip sectionscan determine the strength, or pull-out resistance, of the fully locked pivotal bone anchor assembly. The distal tip sectionsof the collet insertare configured to transfer load from the shank headto the receiver base. Relative motion between the distal tip sectionsand the receiver baseis limited by friction and/or interference between the notched outer surfacesof the distal tip sectionsand the ridged partial spherical seating surfaceof the receiver cavity. In addition, the downward-facing horizontal surfaceof the notchengages with the mating upward-facing horizontal surfaceof the ridgeto provide a positive stop for distal tip pull out relative to the receiver, as well as an indexed single location for the collet insertrelative to the receiver. Assuming that relative motion between the distal tip sectionsand the receiver baseis restricted or substantially prevented, pull-out resistance of the shankis provided by a plurality of shear walls in the collet fingersand distal tip sectionsthat start at the major diameter of the shank headand terminate at the bottom surfaceof the distal tip sections.

64 67 FIGS.- 250 10 264 262 274 272 264 260 266 272 270 270 278 272 266 274 222 264 262 With reference to, illustrated therein is yet another representative embodimentof the pivotal bone anchor assembly that is also substantially similar to the pivotal bone anchor assemblydescribed above, except for modifications to the interface between the partial spherical seating surfaceof the receiver cavity, and to the outer partial spherical surfacesof the distal tip sections. In particular, the partial spherical seating surfaceof the receivercan be modified to include a horizontal, upwardly-facing stepped surfaceat the lower end thereof. In addition, the distal tip sectionsof the collet insertcan be shortened so that, when the collet insertis downwardly deployed into the capture/locking state position, the bottom surfacesof the distal tip sectionssimultaneously engage the upwardly-facing stepped surfacewhile the outer partial spherical surfacesof the distal tip sectionsengage the partial spherical seating surfaceof the receiver cavity.

22 254 264 266 260 274 278 270 250 272 270 22 261 272 261 274 278 272 264 266 262 278 272 266 260 270 260 272 261 20 271 272 222 278 272 It is contemplated that the above-referenced modifications, which serve to establish a seating interface with a stepped surface, may improve the resistance to pull-out of the shank headfrom the receiver sub-assemblyduring assembly, loading, and use. For instance, and similar to the pull-out analyses described above, the interface between the partial spherical seating surfacewith the upwardly-facing stepped surfaceof the receiverand the plurality of outer partial spherical surfacesand bottom surfacesof the shortened distal tip sectionscan determine the strength, or pull-out resistance, of the fully locked pivotal bone anchor assembly. The distal tip sectionsof the collet insertare configured to transfer load from the shank headto the receiver base. Relative motion between the distal tip sectionsand the receiver baseis limited by friction and/or interference between the outer surfacesand bottom surfacesof the distal tip sectionsand the partial spherical seating surfaceand stepped surfacesof the receiver cavity. In addition, the horizontal downward-facing bottom surfacesof the shortened distal tip sectionsengage with the mating horizontal upward-facing stepped surfaceto provide a positive stop for distal tip pull out relative to the receiver, as well as an indexed single location for the collet insertrelative to the receiver. Assuming that relative motion between the distal tip sectionsand the receiver baseis restricted or substantially prevented, pull-out resistance of the shankis provided by a plurality of shear walls in the collet fingersand distal tip sectionsthat start at the major diameter of the shank headand terminate at the bottom surfaceof the distal tip sections.

68 74 FIGS.- 300 10 314 312 324 322 314 316 330 330 312 22 316 330 22 32 322 320 320 328 322 332 330 324 322 314 316 With reference to, illustrated therein is yet another representative embodimentof the pivotal bone anchor assembly that is also substantially similar to the pivotal bone anchor assemblydescribed above, except for modifications to the interface between the partial spherical seating surfaceof the receiver cavityand the outer partial spherical surfacesof the distal tip sections. In particular, the partial spherical seating surfacecan be modified to include a circumferential expansion ring slotthat is sized and shaped to receive a separate expansion ring. The expansion ringcan be uploaded separately into the receiver cavityprior to the uploading of the shank head. The expansion ring slotis sufficiently deep to allow the expansion ringto expand outward to allow passage of the shank headduring uploading, and then to close back around the lower portion of the spherical outer surfacebelow the hemisphere plane. In addition, the distal tip sectionsof the collet insertcan be shortened so that, when the collet insertis downwardly deployed into the capture/locking state position, the bottom surfacesof the distal tip sectionssimultaneously engage the top surfaceof the expansion ringwhile the outer partial spherical surfacesof the distal tip sectionsengage the partial spherical seating surfacethat is located above the circumferential expansion ring slot.

22 304 314 330 324 322 300 322 320 22 311 322 311 322 314 312 300 328 322 332 330 310 320 310 322 311 330 22 321 322 22 328 322 It is contemplated that the above-referenced modifications, which serve to establish a seating interface with expansion ring support, may improve the resistance to pull-out of the shank headfrom the receiver sub-assemblyduring assembly, loading, and use. For instance, and similar to the pull-out analyses described above, the interface between the partial spherical seating surfaceand the expansion ringand the plurality of outer partial spherical surfacesof the distal tip sectionscan determine the strength, or pull-out resistance of the fully locked pivotal bone anchor assembly. The distal tip sectionsof the collet insertare configured to transfer load from the shank headto the receiver base. Relative motion between the distal tip sectionsand the receiver baseis limited by friction and interference between the outer and bottom surfaces of the distal tip sectionsand the partial spherical seating surfaceof the receiver cavityand the expansion ring. In addition, the horizontal downward-facing bottom surfacesof the shortened distal tip sectionsengage with the mating horizontal upward-facing top surfaceof the expansion ringto provide a positive stop for distal tip pull out relative to the receiver, as well as an indexed single location for the collet insertrelative to the receiver. Assuming that relative motion between the distal tip sectionsand the receiver base/expansion ringis restricted or substantially prevented, pull-out resistance of the shankis provided by a plurality of shear walls in the collet fingersand distal tip sectionsthat start at the major diameter of the shank headand terminate at the bottom surfaceof the distal tip sections.

75 81 FIGS.- 350 10 364 362 374 372 364 366 380 373 370 380 362 22 366 380 22 372 370 370 378 372 382 380 374 372 364 With reference to, illustrated therein is yet another representative embodimentof the pivotal bone anchor assembly that is also substantially similar to the pivotal bone anchor assemblydescribed above, except for modifications to the interface between the partial spherical seating surfaceof the receiver cavityand the outer partial spherical surfacesof the distal tip sections. In particular, the partial spherical seating surfacecan be modified to include a circumferential expansion ring slotthat is sized and shaped to receive a separate expansion ring, which is subsequently restrained by tab extensionsprojecting from the collet insert. The expansion ringcan be uploaded separately into the receiver cavityprior to the uploading of the shank head. The expansion ring slotis sufficiently deep to allow the expansion ringto expand outward to allow passage of the shank head. The distal tip sectionsof the collet insertcan be shorted so that, when the collet insertis downwardly deployed into the capture/locking state position, the bottom surfacesof the distal tip sectionssimultaneously engage the top surfaceof the expansion ringwhile the outer partial spherical surfacesof the distal tip sectionsengage the receiver partial spherical seating surface.

372 370 373 372 371 371 373 374 362 368 373 372 370 370 373 380 380 366 350 373 380 366 370 361 380 As can be seen in the drawings, the distal tip sectionsof the collet insertcan be further modified to include tab extensionsthat project radially outward from distal tip sectionsof a plurality of collet fingers. In one embodiment, three of six collet fingerscan include tab extensionswhile the remaining three can have outer partial spherical surfaces. The upper expansion chamber and the conical transition surface portions of the receiver cavitycan also be further modified to include a plurality of vertical recessesthat are sized and shaped to receive the plurality of tab extensionsprojecting radially from the distal tip sectionsof the collet insert. When the collet insertis downwardly deployed into the capture/locking state position, the tab extensionscan slide behind the expansion ringto prevent the outward deflection of the expansion ringinto the expansion ring slotduring loading of the pivotal bone anchor. The tab extensionscan prevent outward expansion of the expansion ringback into its expansion ring slotto better restrict the relative motion between the distal tip sectionsand the receiver baseand expansion ring.

22 354 364 380 374 372 350 372 370 22 361 372 361 374 378 372 364 362 380 378 372 382 380 360 370 360 372 361 380 20 371 372 22 378 372 It is contemplated that the above-referenced modifications, which serve to establish a seating interface with constrained expansion ring support, may improve the resistance to pull-out of the shank headfrom the receiver sub-assemblyduring assembly, loading, and use. For instance, and similar to the pull-out analyses described above, the interface between the partial spherical seating surfaceand the expansion ringand the plurality of outer partial spherical surfacesof the distal tip sectionscan determine the strength, or pull-out resistance, of the fully locked pivotal bone anchor assembly. The distal tip sectionsof the collet insertare configured to transfer load from the shank headto the receiver base. Relative motion between the distal tip sectionsand the receiver baseis limited by friction and interference between the outer surfacesand bottom surfacesof the distal tip sectionsand the partial spherical seating surfaceof the receiver cavityand expansion ring. In addition, the horizontal downward-facing bottom surfacesof the shortened distal tip sectionsengage with the mating horizontal upward-facing top surfaceof the expansion ringto provide a positive stop for distal tip pull out relative to the receiver, as well as an indexed single location for the collet insertrelative to the receiver. Assuming that relative motion between the distal tip sectionsand the receiver baseand the expansion ringis restricted or substantially prevented, pull-out resistance of the shankis provided by a plurality of shear walls in the collet fingersand distal tip sectionsthat start at the major diameter of the shank headand terminate at the bottom surfaceof the distal tip sections.

82 84 FIGS.- 1 59 FIGS.- 1 99 FIGS.- 400 410 410 400 100 410 420 430 100 Illustrated inis yet another representative embodimentof a pivotal bone anchor apparatus or assembly in which the elongate rods and receivers have been replaced with housingsthat provide for adjacent level connection. For example, the housingsof the pivotal bone anchor assembliescan replace the receiverdiscussed above with respect to, with the housingscontaining internal components, such as a modified collet insertand an enclosed pressure ring, that are similar in function to the collet insert and enclosed pressure ring described above as residing in the receivershown in.

82 FIG. 410 412 414 418 416 412 As shown in, in one aspect the housingsof the pivotal bone anchor assembly can be separated into a male housinghaving a male cord or projectionthat is received in pivotal arrangement within a female receptacleof a female housingimmediately adjacent the male housing.

410 420 420 410 22 440 420 22 83 84 FIGS.- The housingoffurther illustrates the separate collet insertthat has been modified to remove the upwardly projecting arm structures that define an insert channel, while still including structures that can provide for the downward deployment of the collet insertwithin the housingto a capture/locking state position around the shank head, prior to the installation of the closure. For example, the collet insertcan include insert ridges that snap into lower capture/locking receiver grooves, the partial spherical seating surface of the receiver cavity can engage the plurality of outer partial spherical surfaces of the distal tip sections to restrain further outward movement for flexing of the distal tip sections, and the plurality of inner partial spherical surfaces of the distal tip sections more forcefully engage the lower portion of the spherical outer surface of the shank headto prevent the shank head from exiting downward through the receiver bottom opening.

430 22 20 Also as described above, the pressure ringis subsequently downwardly deployable from its position in the upper portion of the collet pocket until the upwardly-concave partially spherical bottom surface of the load ring engages the upper portion of the shank head spherical surface. In one aspect the deployment of the pressure ring is sufficient to establish, or further assure, a non-floppy friction fit that holds the position of the receiver sub-assembly relative to the shank head, while still allowing for movement of the receiver sub-assembly relative to the bone anchorwith an applied force.

410 410 22 1 59 FIGS.- With housingsso equipped with these internals, each housingis also able to couple with the above-described shank heads, as generally outlined above with respect to. The receivers and housings thus may be considered different versions of a structural envelope that contains complimentary versions a collet insert and an enclosed pressure ring.

As indicated above, the invention has been described herein in terms of preferred embodiments and methodologies considered by the inventor to represent the best mode of carrying out the invention. It will be understood by the skilled artisan, however, that a wide range of additions, deletions, and modifications, both subtle and gross, may be made to the illustrated and exemplary embodiments of the pivotal bone anchor assembly without departing from the spirit and scope of the invention. These and other revisions might be made by those of skill in the art without departing from the spirit and scope of the invention that is constrained only by the following claims.